Broadband Noncontact Time-Domain Waveform Reconstruction for Near-Field Probing Systems

The time-domain integration method (TDIM) has been widely used for non-contact reconstruction of voltage and current signals on printed circuit board traces. However, its performance is fundamentally constrained by two critical limitations: first, the knee point of the frequency response, which restricts the effective operating bandwidth, and second, frequency response ripples, which degrade measurement accuracy. To overcome these challenges, a novel Odd Harmonic Signal Construction Fourier Transform Method (OHSFM) is proposed for near-field probing systems. The OHSFM addresses the key shortcomings of TDIM in two ways: 1. Bandwidth Expansion: It eliminates the knee-point limitation, extending the measurable bandwidth by at least tenfold compared to TDIM; 2. Enhanced Accuracy: It suppresses distortion caused by ripple and knee point, reducing the peak measurement error from 177% (TDIM) to just 3.2% (OHSFM). Experimental results demonstrate that OHSFM excels in high-frequency microwave and transient pulse measurements, particularly for signals with nanosecond-scale rising edges.